Treating coal



United States Patent This invention relates to a method of treating coaland to coal compositions resistant to degradation.

Coal is susceptible to oxidation. 7 The grinding of coal,

required for certain uses, accelerates the oxidation by exposing newsurfaces, Oxidation of coal is undesirable for several reasons. Forexample, coal storage piles have been destroyed because of spontaneouscombustion; the slow oxidation under conditions that do not permitdissipation of the heat evolved results in increase in temperature,acceleration of oxidation processes, accumulation of more heat untilactive combustion starts. Another costly effect of coal oxidation is theloss of heating value during storage of reserve fuel pile at powerplants. In the case of high volatile matter bituminous C or coal oflower rank, loss in B.t.u. values during storage could amount to to ofthe original heating value of the coal. The stock of coking coal at ametallurgical coke plant may deteriorate to the point that nosatisfactory coke can be produced.

Although it has been proposed to protect coal by coating of the surfacethereof so as to present impervious physical barrier between it and theatmosphere, these treatments have either been ineffective oruneconomical. It has now been found that phosphite esters inhibit theoxidation of coal. The phosphite ester may advantageously be used incombination with a dihydr-otrialkylquinoline. The antioxidant willnormally be within the range of 250-2500 parts per million parts ofcoal. Where the antioxidant :is composed of the aforesaid mixture thephosphite ester should be at least 50% and preferably 85% of the total.Thus, the antioxidant composition will be composed of 50-85% phosphiteester and -50% dihydrotrialkylquinoline.

As an example of the invention, a high volatile bituminous C rank coalground to pass a 40 mesh sieve is treated with 750 parts per million ofantioxidant. This antioxidant is applied to the ground coal in acetoneor methanol solution and the coal so treated is dried at roomtemperature for a few hours to remove the solvent. The course of thedegradation is followed by measuring the oxygen absorption as a functionof time. An untreated sample is run as a control. The oxygen absorptionis conveniently determined by placing samples of the control and treatedmaterial in air-tight containers attached to glass burettes filled withoxygen and measuring the amount of oxygen absorbed. The rate of oxygenuptake for treated samples is significantly lower than for the untreatedsample. The effect of oxidation is followed by periodic determination ofthe heating values. Certain high volatile bituminous B used formetallurgical coke manufacture are usually utilized in coke ovens withina few weeks after mining due to their loss in maximum fluidity producedby oxidation. Maximum fluidity values of the Gieseler plasticity testobtained periodically on untreated and treated samples show that theeffect of oxida tion can be appreciably minimized, especially within thefirst 4 weeks after mining.

Examples of the antioxidant compositions comprise A. 1 part6-dodecyl-1,2-dihydro-2,2,4-trimethylquinoline 5 partstriphenylphosphite B. 1 part6-dodecyl-1,2-dihydro-2,2,4-trimethylquinoline 5 partstri(nonylphenyl)phosphite C. 1 part6-ethoxy-1,Z-dihydro-2,2,4-trimethylquinoline 5 partstri(nonylphenyl)phosphite D. Tri(nonylphenyl)phosphite Compositions A, Band C are applied at a dosage of 750 parts per million parts of coal andComposition D at 625 parts per million parts of coal.

The antioxidants are advantageously applied in either emulsion orsolution form. The antioxidant may be dissolved in an organic solvent asdescribed or dispersed as an aqueous medium and the composition appliedto coal in any suitable manner. Addition of small amounts of a surfaceactive agent facilitates dispersion. It is now customary to wash coal asit comes from the mine. The antioxidant is advantageously appliedthrough adaptation of equipment already installed for washing coal.

A large number of phosphite esters are available and any of these may beemployed in carrying out the method of the present invention. Examplescomprise Triphenylphosphite Tri-o-tolylphosphite Tri-m-tolylphosphiteTri-p-tolylphosphite Trixenyl phosphite Tri-beta-naphthyl phosphiteTri-alpha-naphthyl phosphite Tri-p-isopropylphenyl phosphite Tri-p-tert.butylphenyl phosphite Tri-p-tert. amylphenyl phosphiteTri-p-phenoxyphenyl phosphite T ri-p-benzyloxyphenyl phosphiteTri-p-chlorophenyl phosphite Tri-(4-methyl 2,6-di-tert. butylphenyl)phosphite Tri-(3-methyl 4,6-di-tert. butylphenyl) phosphiteTri-(3-dimethylphenyl) phosphite Tri-(2,4-dimethylphenyl) phosphiteTri-(3,4-dimethylphenyl) phosphite Tri-(2,5-dimethylphenyl) phosphiteTri-(2,4,6-tri-tert. butylphenyl) phosphite Tri-(2-methyl-4,6-di-tert.butylphenyl) phosphite Trio-octylphenyl) phosphite Tri-(p-nonylphenyl)phosphite Tri- (p-decylphenyl) phosphite Tri-(p-undecylphenyl) phosphiteTri-(p-dodecylphenyl) phosphite Tri-(p-tridecylphenyl) phosphiteTri-(p-tetradecylphenyl) phosphite Tri-(p-pentadecylphenyl) phosphiteTri-(p-hexadecylphenyl) phosphite Tri-(p-heptadecylphenyl) phosphiteTri- (p-octadecylphenyl) phosphite Tri-(p-eicosyl-phenyl) phosphiteTri-(Z-ethylhexylphenyl) phosphite p-Octyl-phenyl di(p-nonylphenyl)phosphite p-Nonyl-phenyl di(p-octyl-phenyl) phosphite p-Dodecyl-phenyldi (p-octyl-phenyl) phosphite Tris (di-octyl-phenyl) phosphiteTris(di-nonyl-phenyl) phosphite Tris(p-octyl-phenyl) phosphiteTri(nonyl-phenyl) phosphite Mono octyl-phenyl di(nonyl-phenyl) phosphiteMono(nonyl-phenyl) di(octyl-phenyl) phosphite T-ri dodecyl-phenyl)phosphite Tri(di-nonyl-phenyl) phosphite Tri(p-tert. amyl-phenyl)phosphite Tri(p-octyl-phenyl) phosphite Mono(o-sec. amyl phenyl)phosphite Mono(p-l,1,3,3-tetramethyl butyl phenyl) phosphiteMono(2,4-di-sec. amyl phenyl) phosphite Mono(2-tert.butyl-5-methylphenyl) phosphite Mono(2,4-di-tert. butyl-5-rnethyl phenyl) phosphiteMono(nonyl phenyl) phosphite Mono(dodecyl phenyl) phosphiteMono(di-nonyl phenyl) phosphite Mono(p-tert. amyl phenyl) phosphiteMono(n-hexyl phenyl) phosphite Mono(n-heptyl phenyl) phosphite Mono(p-n-decyl phenyl) phosphite Mono(p-n-pentadecyl phenyl) phosphiteMono(p-n-hexadecyl phenyl) phosphite Mono(p-noctadecyl phenyl) phosphiteMono(alkylaryl) phosphite Mono(di-sec. amyl phenyl) phosphiteMono(2-tert, butyl 4-methyl phenyl) phosphite Mno(phenyl) phosphiteMono(di-tert. butyl m-cresyl) phosphite Ethylene phenyl phosphiteEthylene 2-chlorophenyl phosphite Ethylene 3-chlorophenyl phosphiteEthylene 4-chlorophenyl phosphite Ethylene Z-methylphenylephosphiteEthylene 3-methylphenyl phosphite Ethylene 4-methylphenyl phosphiteEthylene 4-ethylphenyl phosphite Ethylene 2-cyclohexylphenyl phosphiteEthylene 4-octylphenyl phosphite Ethylene 3-isobutylpheny-1 phosphiteEthylene 2-dodecylphenyl phosphite Ethylene 4-ethoxyphenyl phosphiteEthylene 4-octyloxyphenyl phosphite 2-cthylhexyl bis (p-octylphenyl)phosphite Z-ethylhexyl diphenyl phosphite Bis(2-ethylhexyl) phenylphosphite Bis(2-ethylhexyl) o-tolyl phosphite Bis(2-ethylhexyl) p-tolylphosphite Bis(2-ethylhexyl) p-octylphenyl phosphite Allyl di -o-tolylphosphite Allyl bis(p-nonylphenyl) phosphite 3-cyclohexen-1-ylmethyldi-o-tolyl phosphite Di-(dodecyl) mono(nonylphenyl) phosphite Di-(octyl)mono(octyl phenyl) phosphite Di-(decyl) mono(n'onylphenyl) phosphiteDi-(nonyl) mono(decyl phenyl) phosphite Di-(nonyl) mono(dodecylpheny1)phosphite Di-(2-octyl) mono(nonyl phenyl) phosphite Di-(nonyl)mono(nonyl phenyl) phosphite Di-(undecyl) mono (nonyl phenyl) phosphiteDi-(nonyl) mono(octyl phenyl) phosphite Di-(nonyl) mono(undecy1 phenyl)phosphite Similarly, the dihydroquinoline antioxidants are well knownand suitable preservatives may be selected therefrom. Although thequinolines are preferably used in conjunction with phosphite esters theymay be employed neat for preservation of coal. Examples of suitablequinoline antioxidants comprise 2,2,4-trialkyl-1,2-dihydro-6- aralkylsubstituted quinolines, as for example2,2,4-trimethyl-1,2-dihydro-6-aralkylquinolines wherein the aralkyl isbenzyl, 1-benzyl-2-phenethyl, l-phenyl-isopropyl or l-p-tolyl-isopropyl.Still further examples are 4 2,2,4-trimethyl-1,Z-dihydroquinolinepolymeric 2,2,4-trimethyl-1,Z-dihydroquinoline2-methyl-2,4-diethyl-1,2-dihydroquinoline2-methyl-2,4-diisopropyl-l,Z-dihydroquinoline6-methoxy-1,2-dihydro-2,2,4-trimethylquinoline6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline6-propoxy-l,2-dihydro-2,2,4-trimethylquinoline6-isopropoxy-1,2-dihydro-2,2,4-trimethylquinoline6-butoxy-1,2-dihydro-2,2,4-trimethylquinoline6-hexoxy-1,Z-dihydro-2,2,4-trimethylquinoline6-phenoxy-1,2-dihydro-2,2,4-trimethylquinoline6-butoxyethoxy-1,2-dihydro-2,2,4-trimethylquinoline6-methoxyethoxy-1,2-dihydro-2,2,4-trimethylquinoline6-diethylarnino-1,2-dihydro-2,2,4-trimethylquinoline6-butyl-1,2-dihydro-2,2,4-trimethylquinoline and6-phenyl-l,2-dihydro-2,2,4-trirnethylquinoline It is intended to coverall changes and modifications of the examples of the invention hereinchosen for purposes of disclosure which do not constitute departuresfrom the spirit and scope of the invention.

What is claimed is:

1. A composition comprising coal having admixed therewith a small amountsufiicient to inhibit oxidation of a phosphite ester antioxidant and a1,2-dihydroquinoline antioxidant.

2. A composition comprising coal having admixed therewith a small amountsufiicient to inhibit oxidation of a phosphite ester antioxidant.

3. A composition comprising coal having admixed therewith a small amountsufficient to inhibit oxidation of tri(alky-lphenyl) phosphiteantioxidant.

4. A composition comprising coal admixed with a small amount suflicientto inhibit oxidation of tri(nonyl phenyl) phosphite.

5. A composition comprising coal admixed with a small amount sufiicientto inhibit oxidation of a tri(nonyl phenyl) phosphite and6-dodecyl-1,2-dihydro-2,2,4-trimethylquinoline.

6. A composition comprising coal admixed with a small amount sufficientto inhibit oxidation of a dihydroquinoline antioxidant.

7. A composition comprising coal admixed with a small amount suflicientto inhibit oxidation of 6-alkoxy- 1,2-dihydro-2,2,4-trimethylquinoline.

8. A composition comprising coal admixed with a small amount sufiicientto inhibit oxidation of 6-alkyl-1,2- dihydro-2,2,4-trimethylquinoline.

References Cited by the Examiner UNITED STATES PATENTS 2,365,974 12/1944 Schreiber 252-400 X 2,530,774 11/1950 Kehe et al 252-401 X2,839,563 6/ 8 Hechenbleikncr. 3,115,465 12/1963 Orlotf et a1.

DANIEL E. WYMAN, Primary Examiner. CARL F. DEES, Assistant Examiner.

1. A COMPOSITION COMPRISING COAL HAVING ADMIXED THEREWITH A SMALL AMOUNTSUFFICIENT TO INHIBIT OXIDATION OF A PHOSPHITE ESTER ANTIOXIDANT AND A1,2-DIHYDROQUINOLINE ANTIOXIDANT.